1.1  Introduction

Civil work is a very essential
movement for the growth. The present civil work for create any road and rail
network work is the cement reinforcement concrete . This cement reinforcement
concrete contains cement, fine and coarse  aggregates and steel . The manufacture of
these material shall produce the significant quantity of dangerous waste. Therefore
for sustainable development moreover the manufacturing of the constructional
materials need toward to be reduced or usage of  local throw away material  has been used .

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Concrete
is a combination of cement, fine aggregate (sand), coarse aggregates (gravel or
crushed stone), and water. Concrete is the most generally used construction
material in the whole  world. Concrete
are like in composition to mortars which are used to link unit masonry.
Mortars, however, are usually made with the  sand as the soil aggregate, whereas  the concrete contains both the fine aggregates
and much larger size aggregates and hence usually have superior in  strength. Concrete consequently has  much wider range of structural applications, plus
pavements, footings, pipes, unit masonary , floor slab , beams, column, wall,
dam, and tank. There are so many unusual type of concrete used in the civil
work according to their uses.

Important
properties of concrete, governing design of a concrete mix, are strength,
durability, workability, economy. Toughness of concrete means potential of
concrete to resists its breakdown and decay. Workability is a calculate of the relieve
through which a fresh mix of the concrete or mortar can be mix, thus handled,
transported, placed and finished among a smallest amount loss of homogeneity
and with no bleeding or segregation in the completed product. It depend on
the  water in the mix  ratio of coarse agg. and fine aggregate,
particle obstruction and interlocking etc. Mixing of concrete shall be done with
hand mixing or machine mixing. Concrete should be systematically compacted through
the operation of placing and shall be suitably placed roughly reinforcement.
Concrete may be compacted manually by rodding, tamping, and sometime inner or
immersion vibrator, outer or form vibrator, surface vibrator shall be used for
the compaction purposes. Concrete should be properly cured for ahead its
strength and hardness.

In
the good concrete the ingredients  should
be of right proportioned, solid enough to be transport or placed in such a way
that the ingredient must not be segregated from each other. Moreover the good
concrete shall be workable and can be compacted. In the mixing of clean
concrete and in curing of hardened concrete water is required. Potable water,
which is fit for human drinking, is generally considered as be suitable for
concreting. Concrete shall be workable in clean state, and must have impermeable
and durable in toughened state.

Grades
of concrete is represent in the conditions of a number preceded by the letter
‘M’. M refers to the “mix” viz. aggregate, sand, cement. And the number denotes
characteristic compressive strength of 150 mm cubes at 28 days in MPa (N per mm^2).The
“mix” for a specific grade involves the economical selection of relative percentage
of cement, fine aggregate, coarse aggregate and water(admixture, if any).

To
modify the  property of concrete some
chemical & mineral admixture has been  used. Chemical admixture is – retarders (such
as sugar &  the other chemicals is used
in hot weather concreting and in ready-mixed concreting), accelerator (such as
calcium chloride is used in cold weather ) water-reducer,
superplasticizer,air-entraining agent (such as animal/vegetable fats and oils),bonds
admixture . Mineral admixture i.e. very fine-grained inorganic material having
pozzolanic or latent hydraulic property is added to the concrete mix to get
better the properties of concrete. Some mineral admixture are Fly ash, Silica
fume, Ground granulated blast furnace slag (GGBFS or GGBS), High reactivity
Metakaolin (HRM) etc.

 

1.2 Methods
of improving strength to structure are :-

1.2.1   Rice
husk ash (RHA) :- Rice husk ash  is an experimented for the replacement of
cement. It is reported in that locally available rice husk ash could be used as
partial replacement for ordinary Portland cement. Rice husk mostly are the
coatings of seeds or grains of rice. Rice husk protects the seeds during the
growing season , since it ha been formed from hard materials ,including silica
and lignin. The husk is generally indigestible to humans as well as for  the environment. When the rice is ready , then
by the  mechanical methods or by the  man power  rice can be separate from  rice hulls or husks . The Combustion of rice
hulls results  rice husk ash. This ash is
the prospective supply of amorphous reactive silica, which have a varieties of
applications in material science. Most of the ashes are used in the making of
portland cement.  The ash also is the
very good thermal insulation material. This fineness of the ash has also make
its a very good applicant for the sealing of fine cracks in civil structures,
where it could be break in deeper then the conventional cement sand mixture.
The number of possible uses for rice husk ash(RHA) included absorbents for oils
and chemicals, a source of silicon, insulation powder in steel mills, as
repellents in the form of ‘vinegar-tar’ release agent in the ceramics modern as
the insulation material. Rice husk could also be burnt into the ash that
fulfill the physical characterstics and chemical composition of mineral
admixture. Pozzolanic activity of rice husk ash depends on (1) is silica
content (2) is silica crystallization phase and  (3) is size and surface area of ash particle.
In adding up, ash  mustly contain only little
amount of carbon. The optimized rice husk ash prohibited by burn or  by grinding, have been used as the pozzolanic
material in cement and concrete. Using it provides the several advantages such
as improved strength and durability properties and environmental profits linked
to the disposal of waste materials and to decrease carbon dioxide emissions.

Rice husk ash has been used in the concrete
construction as an another of cement. The rice 
milling industry gaves the bi-product rice husk. Due to the growing rate
of ecological pollution and the thoughtfulness of sustainability factor has
made the idea of utilize rice husk.

The reason behind the practice of rice husk as
an another for cement in concrete manufacturing are explained in the additional
study. The rice husk itself has a very rough surface which is rude in nature.